Theoretical Verification of Dynamic Lumbar Interspinous Process Stabilization Device with Memory Alloys / 中国医疗器械杂志

To find an effective method of minimally invasive treatment combining prevention and assistance in the middle zone of conservative treatment and fusion surgery for lumbar degenerative diseases, through the clinical effect observation and the advantage and disadvantage comparison of several commonly used lumbar interspinous dynamic stabilization systems, by analyzing the physiological structure, biomechanics and relevant data of lumbar interspinous processes, based on fully understanding of memory alloy materials, a new dynamic lumbar interspinous fixation device with a memory alloy material has been independently designed and researched, which can not only reconstruct the normal biomechanical characteristics of the lumbar spine and satisfy the normal activities of the human spine, but also avoid damage to the original structure and reduce the incidence of postoperative complications. In addition, the device can be used to optimize the current therapeutic methods. According to our research, the dynamic lumbar interspinous process stabilization device with a memory alloy has theoretically achieved satisfactory results, which can be used to overcome the shortcomings of the existing technology and is superior to the current several dynamic lumbar interspinous process stabilization systems.

Long-Term Outcome of Dynesys Dynamic Stabilization for Lumbar Spinal Stenosis / 中华医学杂志(英文版)

<p><b>Background</b>Many clinical studies over the past decade have indicated positive outcomes for patients treated with Dynesys dynamic stabilization for lumbar degenerative disease. However, long-term outcomes of Dynesys for lumbar spinal stenosis are rarely reported. The aim of this study was to analyze the long-term clinical and radiologic outcomes for patients with lumbar spinal stenosis treated with Dynesys stabilization.</p><p><b>Methods</b>Thirty-eight patients with lumbar spinal stenosis were treated with Dynesys stabilization from July 2008 to March 2010. The minimal duration of follow-up was 72 months. The patients were divided into stenosis and spondylolisthesis groups according to degenerative spondylolisthesis. Clinical outcomes were evaluated using the Oswestry Disability Index (ODI) and visual analog scale (VAS). Radiographic evaluations included range of motion (ROM) and the disc heights of stabilized segments and the upper adjacent segments. We also evaluated the occurrence of radiographic and symptomatic adjacent segment degeneration (ASD).</p><p><b>Results</b>There were 23 patients in stenosis group and 15 patients in spondylolisthesis group. The ODI scores were significantly improved at the final follow-up evaluation, as compared to the baseline values (16.1 ± 5.7 vs. 57. 2 ± 14.2, t = 61.41, P < 0.01). The VAS scores for back and leg pain were significantly improved from 4.82 ± 0.89 and 4.04 ± 0.82 preoperatively to 0.93 ± 0.61 and 0.54 ± 0.51 postoperatively (t = 6.59, P < 0.01, and t = 5.91, P < 0.01, respectively). There were no differences between the two groups with respect to VAS and ODI scores. The ROM of stabilized segments decreased significantly from 7.8° ± 2.4° to 4.5° ± 1.5° (t = 7.18, P < 0.05), while the upper adjacent segments increased significantly from 8.3° ± 2.4° to 10.4° ± 2.4° (t = 2.87, P = 0.01). The change in disc height of stabilized segments was not significant (11.9 ± 2.1 preoperatively vs. 12.5 ± 1.5 postoperatively, t = 1.43, P = 0.15), whereas the decrease in disc height of the upper adjacent segments was significant (12.5 ± 2.0 preoperatively vs. 11.0 ± 1.7 postoperatively, t = 2.94, P = 0.01). The occurrence of radiographic and symptomatic ASD was 16% (6/38) and 3% (1/38), respectively.</p><p><b>Conclusions</b>Decompression and Dynesys stabilization for lumbar stenosis with or without spondylolisthesis showed good long-term clinical and radiographic results. Lumbar stenosis with or without Grade I spondylolisthesis, particularly in patients <60 years of age with mild-to-moderate lumbar disc degeneration, would be one of the main indications for the Dynesys system.</p>

Enlargement of Neural Foramina and Dynamic Stabilization in Spondylolisthesis without Restoring the Alignment: Technical Note

It is well known that the cause of radiculopathy is the compression of the nerve root within the foramina which is narrowed secondary to sliding of the corpus and reduced disc height. In some patients, unroofing the foramen does not resolve this problem. We described a new decompression technique using pedicle removal and transpedicular dynamic instrumentation to stabilization the spine. We performed this operation in 2 patients and achieved very good results.

Radicular Pain due to Subsidence of the Nitinol Shape Memory Loop for Stabilization after Lumbar Decompressive Laminectomy

A number of dynamic stabilization systems have been used to overcome the problems associated with spinal fusion with rigid fixation recently and the demand for an ideal dynamic stabilization system is greater for younger patients with multisegment disc degeneration. Nitinol, a shape memory alloy of nickel and titanium, is flexible at low temperatures and regains its original shape when heated, and the Nitinol shape memory loop (SML) implant has been used as a posterior tension band mostly in decompressive laminectomy cases because the Nitinol implant has various characteristics such as high elasticity and a tensile force, flexibility, and biological compatibility. The reported short-term outcomes of the application of SMLs as posterior column supporters in cervical and lumbar decompressive laminectomies seem to be positive, and complications are minimal except for the rare occurrence of pullout and fracture of the SML. However, there was no report of neurological complications related to neural compression in spite of the use of the loop of SML in the epidural space. The authors report a case of delayed development of radiating pain caused by subsidence of the SML resulting epidural compression.

Effect of Device Rigidity and Physiological Loading on Spinal Kinematics after Dynamic Stabilization : An In-Vitro Biomechanical Study

OBJECTIVE: To investigate the effects of posterior implant rigidity on spinal kinematics at adjacent levels by utilizing a cadaveric spine model with simulated physiological loading. METHODS: Five human lumbar spinal specimens (L3 to S1) were obtained and checked for abnormalities. The fresh specimens were stripped of muscle tissue, with care taken to preserve the spinal ligaments and facet joints. Pedicle screws were implanted in the L4 and L5 vertebrae of each specimen. Specimens were tested under 0 N and 400 N axial loading. Five different posterior rods of various elastic moduli (intact, rubber, low-density polyethylene, aluminum, and titanium) were tested. Segmental range of motion (ROM), center of rotation (COR) and intervertebral disc pressure were investigated. RESULTS: As the rigidity of the posterior rods increased, both the segmental ROM and disc pressure at L4-5 decreased, while those values increased at adjacent levels. Implant stiffness saturation was evident, as the ROM and disc pressure were only marginally increased beyond an implant stiffness of aluminum. Since the disc pressures of adjacent levels were increased by the axial loading, it was shown that the rigidity of the implants influenced the load sharing between the implant and the spinal column. The segmental CORs at the adjacent disc levels translated anteriorly and inferiorly as rigidity of the device increased. CONCLUSION: These biomechanical findings indicate that the rigidity of the dynamic stabilization implant and physiological loading play significant roles on spinal kinematics at adjacent disc levels, and will aid in further device development.

Dynesys dynamic fixation and lumbar spinal fusion for treatment of lumbar degenerative disease: A clinical comparative study / 第二军医大学学报

To evaluate the value of Dynesys dynamic fixation for treatment of lumbar degenerative disease by comparing with lumbar spinal fusion. Methods The clinical data of 60 patients with lumbar degenerative disease, who were treated inChanghai Hospital from June 2009 to June 2010, were retrospectively analyzed. Twenty-six patients, including 15 males and 11 females, with age ranging 32-56 years (average [42.45 ± 10.12] years), received Dynesys implantation for segments L4-L5 (13 cases) and L5-S1 (13 cases). Thirty-four patients, including 20 males and 14 females, with age ranging 38­60 years(average [45.24 ± 12.15] years), received fusion implantation for segments L4-L5 (18 cases) and L5S (16 cases). The following parameters were observed and compared between the two groups: operation time, blood loss, hospital stay, preoperative Oswestry disability index (ODI), ODI at last follow-up, low back and leg pain visual analogue scale (VAS), results of health status questionnaire (SF-36), segmental angulation degree of lumbar spine, and intervertebral height. Results All the 60 patients were followed up for 3-4 years (average [3.2 ± 0.2] years). The operation time and intra-operative blood loss were significantly different between the two groups (P < 0.05), and no difference was found for average hospital days. The ODI, VAS, and SF-36 clinical scores at last follow-up were significantly improved compared with those before operation in the two groups (P < 0.01), with the improvement in Dynesys group being more significant than the fusion group (P < 0.01). The segmental angulation degree of lumbar spine had no noticeable improvement in the two groups at last follow- up, and there were no significant differences between the two groups. There was no intervertebral height loss at the last follow-up in the two groups, and there was no significant difference in intervertebral heights between the two groups. Conclusion Dynesys dynamic lumbar fixation shows no more advantages in terms of radiological results compared with the fusion group. Moreover, fusion fixation is not suggested to have more adjacent segment degeneration (ASD) than Dynesys dynamic lumbar fixation. But clinically Dynesys dynamic lumbar fixation yields a greater improvement, with the advantages of less bleeding and shorter operation time. In middle-aged and elderly patients with degenerative diseases, Dynesys dynamic lumbar fixation is an acceptable choice.

Back Muscle Changes after Pedicle Based Dynamic Stabilization

OBJECTIVE: Many studies have investigated paraspinal muscle changes after posterior lumbar surgery, including lumbar fusion. However, no study has been performed to investigate back muscle changes after pedicle based dynamic stabilization in patients with degenerative lumbar spinal diseases. In this study, the authors compared back muscle cross sectional area (MCSA) changes after non-fusion pedicle based dynamic stabilization. METHODS: Thirty-two consecutive patients who underwent non-fusion pedicle based dynamic stabilization (PDS) at the L4-L5 level between February 2005 and January 2008 were included in this retrospective study. In addition, 11 patients who underwent traditional lumbar fusion (LF) during the same period were enrolled for comparative purposes. Preoperative and postoperative MCSAs of the paraspinal (multifidus+longissimus), psoas, and multifidus muscles were measured using computed tomographic axial sections taken at the L4 lower vertebral body level, which best visualize the paraspinal and psoas muscles. Measurements were made preoperatively and at more than 6 months after surgery. RESULTS: Overall, back muscles showed decreases in MCSAs in the PDS and LF groups, and the multifidus was most affected in both groups, but more so in the LF group. The PDS group showed better back muscle preservation than the LF group for all measured muscles. The multifidus MCSA was significantly more preserved when the PDS-paraspinal-Wiltse approach was used. CONCLUSION: Pedicle based dynamic stabilization shows better preservation of paraspinal muscles than posterior lumbar fusion. Furthermore, the minimally invasive paraspinal Wiltse approach was found to preserve multifidus muscles better than the conventional posterior midline approach in PDS group.

NFlex Dynamic Stabilization System : Two-Year Clinical Outcomes of Multi-Center Study

OBJECTIVE: Pedicle-based dynamic stabilization systems, in which semi-rigid rods or cords are used to restrict or control spinal segmental motion, aim to reduce or eliminate the drawbacks associated with rigid fusion. In this study, we analyzed the two-year clinical outcomes of patients treated with the NFlex (Synthes Spine, Inc.), a pedicle-based dynamic stabilization system. METHODS: Five sites participated in a retrospective study of 72 consecutive patients who underwent NFlex stabilization. Of these 72 patients, 65 were available for 2-year follow-up. Patients were included based on the presence of degenerative disc disease (29 patients), degenerative spondylolisthesis (16 patients), lumbar stenosis (9 patients), adjacent segment degeneration (6 patients), and degenerative lumbar scoliosis (5 patients). The clinical outcome measures at each assessment were Visual Analogue Scale (VAS) to measure back pain, and Oswestry Disability Index (ODI) to measure functional status. Radiographic assessments included evidence of instrumentation failure or screw loosening. RESULTS: Sixty-five patients (26 men and 39 women) with a mean age of 54.5 years were included. Mean follow-up was 25.6 months. The mean VAS score improved from 8.1 preoperatively to 3.8 postoperatively, representing a 53% improvement, and the ODI score from 44.5 to 21.8, representing a 51% improvement. Improvements in pain and disability scores were statistically significant. Three implant-related complications were observed. CONCLUSION: Posterior pedicle-based dynamic stabilization using the NFlex system seems effective in improving pain and functional scores, with sustained clinical improvement after two years. With appropriate patient selection, it may be considered an effective alternative to rigid fusion.

Biomechanical study of a new lumbar dynamic internal fixation system / 中华创伤杂志

Objective To investigate effect of a new lumbar dynamic internal fixation system(DIFS)on the stability and intradiscal pressure of lumbar segment.Methods Eight fresh calf lumbar specimens were collected to build test models,which were loaded with pure moments of 8 N·m in flexion/extension,lateral bending,and rotation planes.The test states included intactness,destabilization,dynamic fixation,semi-rigid fixation,and solid fixation.The data were collected from the third loading cycle to determine range of motion and neutral zone of corresponding segments,and the intradiscal pressure.Results Destabilization significantly increased segmental range of motion and neutral zone in three motion planes without obvious influence on intradiscal pressure.The three fixation systems were all able to stabilize and load destabilizing segments.DIFS restored the range of motion of unstable segment to 77％,60％,61％ and 70％ of the intact level in anterior flexion,posterior extension,lateral bending and rotation planes.Meanwhile,DIFS bore 45％,29％ and 40％ of tbe intradiscal load in lateral bending,rotation and flexion directions,but 100％ of the intradiscal load in back extension.The stability and intradiscal pressure of adjacent segments were not affected by the test states.Conclusion DIFS can effectively restore range of motion of unstable segments and share appropriate intradiscal load in most directions.

Estabilización dinámica con ligamentoplastia interespinosa en discopatía degenerativa de columna vertebral lumbar / Dynamic stabilization with interspinous ligamentoplasty in degenerative discopaty of lumbar spine

El tratamiento de la Discopatía Degenerativa lumbar, mediante dispositivo suave de estabilización dinámica, con el uso de ligamento para reforzamiento interespinoso, altera favorablemente el movimiento y la transmisión de carga de un segmento vertebral, proporcionando estabilidad y previniendo la enfermedad del segmento adyacente. Por lo tanto se realiza un estudio prospectivo, longitudinal con 25 pacientes con edades comprendidas entre 15 y 58 años, con diagnóstico de Discopatia degenerativa lumbar; con estudios de imágenes previos con radiografias en proyección AP, lateral y laterales dinámicas además de Resonancia Magnética, con los cuales se confirmo el diagnóstico, al igual que control radiológico postoperatorio, a los que se les practico semihemilaminectomia mas discectomíamas foraminectomía mas ligamentoplastia interespinosa del segmento afectado y adyacentes. Se obtuvo como resultado mejoría clínica inmediata en la mayoría de los pacientes y con pronto reintegro a sus actividades habituales luego de la cirugía.

The treatment of lumbar degenerative discopaty, by means of a soft dynamic stabilization device, with the use of ligament for interspinous reinforcement, alter favorably the movement and load transmission of a vertebral segment, providing stability and preventing the disease of the adjacent segment. Therefore a prospectivelongitudinal study is carried out on 25 patients with ages ranging from 15 to 58 years, with a lumbar degenerative disease diagnosis; previous radiographicstudies in AP, lateral and dynamic-laterals projectionsand also Magnetic Resonance Imaging confirm the diagnosis, along with postoperative radiological controls. The patients received semi-hemilaminectomy plus discectomy plus foraminectomy plus interspinous ligamentoplasty of affected and adjacent segments. As result, inmediate clinical improvement in most patients was obtained and a soon return to their usual activities after the surgery.

The analysis on short-term clinical efficacy of In-Space after decompressive laminectomy for treatment of degenerative lumbar spinal stenosis with vertebral instability / 中国医师进修杂志

Objective To investigate the difference of short-term clinical efficacy between decompressive laminectomy into In-Space and simple decompressive laminectomy for treatment of lumbar spinal stenosis with vertebral instability.Methods Thirty-three patients with lumbar spinal stenosis with vertebral instability admired from May 2009 to July 2010,were divided into two groups by random number table.Group A of 16 cases was treated with laminectomy decompression and placement In-Space,group B of 17 cases was treated with laminectomy decompression.Lumbar anteroposterior,lateral and flexion-extension X-ray films,preoperatively,and the follow-up were used to measure anterior and posterior disc height,foraminal height,segmental lordotic angle at surgical level.Using Oswestry disability index (ODI) and the visual analogue scale (VAS) to evaluate the clinical efficacy.Results All patients were followed up for (13.20 ± 2.91 ) months (range 6 to 21 months).The anterior disc height after operation of group A was slightly decreased compared with the preoperative(P＞ 0.05 ),the posterior disc height at 1 day after operation and foraminal height after operation of group A were significantly increased compared with the preoperative (P＜ 0.05).The anterior and posterior disc height,foraminal height of group B at 1 day,1 month,3 months after operation were no significantly different compared with the preoperative (P ＞ 0.05 ),at 6 months after operation and the end of follow-up were significantly decreased compared with the preoperative or 1 day after operation (P ＜ 0.05 ).Activity of lumbar vertebra by preoperative 9.86° ± 1.90° decreased to the end of followup 5.60° ± 2.02°in group A,while activity of lumbar vertebra by preoperative 9.89° ± 2.00°increased to the end of follow-up 10.76° ± 3.14° in group B.At the end of follow-up,lumbar back pain VAS,ODI score [ (2.02 ± 1.98 ),( 20.18 ± 18.80) scores ] of group A were significantly lower than those of group B [ (4.15 ±2.36),(30.39 ± 16.62 ) scores ],the differences were statistically significant (P ＜ 0.05 ).No patient suffered In-Space loosening,fracture and emerge.Conclusion The operation of In-Space can maintain spinal mobility and stability as well as avoiding lumbar vertebral instability,and its short-term efficacy is satisfactory.

Avaliação da resposta clínica da estabilização pedicular, sem fusão, em pacientes com lombalgia / Evaluación de la respuesta clínica de la estabilización pedicular, sin fusión, en pacientes con lumbalgia / Clinical outcomes with non-fusion stabilization in low back pain

OBJETIVO: Avaliar o resultado clínico do tratamento cirúrgico da doença discal degenerativa (DDD) com o uso de sistemas de estabilização pedicular sem fusão em 22 pacientes na cidade de Aracaju/Sergipe. MÉTODOS: Foram utilizadas escala visual analógica da dor (EVA) e qualidade de vida ( questionários Oswestry e Roland Moris) no pré-operatório e seis meses após o tratamento cirúrgico instituído. De acordo com as queixas clínicas e as alterações morfofisiológicas encontradas nos exames complementares de imagem, grau de acometimento articular (artrose facetária), doença discal em níveis adjacentes, microdiscectomias prévias, optou-se pela utilização de implantes que permitem graus de mobilidade variáveis. RESULTADOS: Dos 22 pacientes incluídos no estudo, 16 eram do sexo masculino e seis do sexo feminino, com média de idade de 41,77 ± 11,6 anos. Foi estabilizado um total de 43 níveis, sendo a instrumentação de L4 a S1 a mais frequente (12) e o sistema mais utilizado foi a placa Dinamika® (GMReis) para dois níveis (08), com fusão do nível inferior (estabilização híbrida). Houve melhora importante da sintomatologia quando observamos a diminuição da EVA no pré-operatório (8,59±1,1) e 6 meses no pós-operatório (2,41±1,8), com melhora na qualidade de vida nas escalas de Oswestry e Roland Moris (ODI pré: 55,18 ± 15,5 e ODI pós: 13,91 ± 13,1 ; RM pré: 27,23 ± 4,9 e RM pós: 41,68 ± 4,8) respectivamente. CONCLUSÃO: Apesar de todos os pacientes incluídos no estudo terem obtido melhora expressiva tanto na qualidade de vida como na diminuição da sintomatologia, novos estudos biomecânicos devem ser realizados a fim de se padronizar uma abordagem eficiente no tratamento dessa patologia.

OBJECTIVE: To evaluate the clinical outcome of surgical treatment of degenerative disc disease (DDD) with the use of pedicular stabilization systems without fusion in 22 patients in the city of Aracaju/Sergipe. METHODS: We used the visual analogic scale (VAS) and quality of life questionnaires (Oswestry and Roland Moris) preoperatively and 6 months after surgical treatment. According to the clinical symptoms and morpholophysiological changes found in the imaging exams, articular changes (facet degeneration), disc disease at adjacent levels, previous microdiscectomy, were determinant parameters for chose the use of implants that allow varying degrees of mobility. RESULTS: Of the 22 patients studied, 16 were male and six female with mean age of 41.77±11.6 years.A total of 43 levels were stabilized and the instrumentation from L4 to S1 was the most frequent segment (12) and the Dinamika® (GMReis - Brazil) plate for 2 levels was the most frequent used system (08), with fusion of the lower level (hybrid stabilization). There was significant improvement in symptoms when we observe a decrease of VAS preoperatively (8,59±1,1)and 6 months postoperatively (2,41±1,8) with improvement in quality of life scores in Oswestry and Roland Moris questionnaires (ODI pre: 55,18±15.5 and ODI post: 13,91±13,1 ; RM pre: 27,23 ± 4,9 e RM post: 41,68 ± 4,8), respectively. CONCLUSION: Although all patients included in the study had achieved a significant improvement both in quality of life and in reducing symptoms, further biomechanical studies should be performed in order to standardize an efficient approach to treat this pathology.

OBJETIVO: Evaluar el resultado clínico del tratamiento quirúrgico de la enfermedad del disco degenerativa (EDD) con la utilización de los sistemas de estabilización pedicular sin fusión en 22 enfermos en la ciudad de Aracajú/Sergipe. MÉTODOS: Fueron utilizadas escalas visual analógica del dolor (EVA) y de calidad de vida (cuestionarios Oswestry e Rolland Morris) antes de la cirugía y seis meses después del tratamiento quirúrgico realizado. De acuerdo con las quejas clínicas y las alteraciones morfofisiológicas encontradas en los exámenes complementarios de imagen, grado de acometimiento articular (artrosis de las facetas), enfermedad discal en niveles adyacentes, microdiscectomías anteriores, se optó por la utilización de implantes que permiten grados de movilidad variables. RESULTADOS: De los 22 enfermos que se incluyeron en el estudio, 16 eran del sexo masculino, y seis del sexo femenino, con el promedio de edad de 41,77 años, más o menos 11,6 años. Se estabilizó un total de 43 niveles, siendo la instrumentación de L4 a S1 la más frecuente (12) y el sistema más utilizado fue la placa Dinamika® (GMReis) para dos niveles (08), con fusión del nivel inferior (estabilización híbrida). Hubo mejoría importante de la sintomatología cuando observamos la disminución del EVA antes del procedimiento cirúrgico (8,59 más o menos 1,1) y seis meses después del procedimiento quirúrgico (2,41 más o menos 1,8), con mejora de la cualidad de vida segúnlas escalas de Oswestry e Rolland Morris (ODI antes: 55,18 más o menos 15,5 y ODI después: 13,91 más o menos 13,1; RM antes: 27,23 más o menos 4,9 y RM después: 41,68 más o menos 4,8), respectivamente. CONCLUSIÓN: Aunque todos los enfermos incluidos en el estudio hayan obtenido una mejoría significativa tanto en la calidad de vida como en la disminución de la sintomatología, nuevos estudios biomecánicos deberán ser realizados para que se llegue a estandarizar un abordaje eficiente en el tratamiento de la patologia.

Early evaluation of Wallis interspinous dynamic stabilization system in treatment of lumbar degenerative disease / 中国医师进修杂志

Objective To evaluate the early effect of Wallis interspinous dynamic stabilization system (Wallis system) in treatment of lumbar degenerative disease. Methods From January 2008 to Jan-uary 2009,21 patients(23 intervertebral spaces) with early lumbar disc herniation and lumbar spinal stenosis were treated with Wallis system. Four intervertebral spaces of L_(3-4) 19 intervertebral spaces of L_(4-5). Observed the time of total operation and implantation,the blood loss,and early recovery. The patients' visual analogue scale (VAS) and Oswestry disability index (ODI) scores were evaluated before and after operation. Results All patients were followed up for average (12.5 ± 0.4) months (7-18 months) after operation. The VAS and ODI scores at 7 days after operation dropped from (7.5 ± 1.5), (40.0 ± 2.0) scores before operation to (2.5 ± 0.5), (23.0 ± 1.5) scores (P < 0.01). Conclusion It is safe and easy to use Wallis system in the treatment of lumbar degenerative disease, with the advantage of mini-invasion and early effect.

Outcomes and radiographs changes of lumbar degeneration disease treated by dynamic stabilization device / 国际外科学杂志

Objective To observe the clinical therapeutic outcomes and the radiographs changes of lumbar degeneration disease treated by dynamic stabilization device (Wallis). Methods Eighty-four cases of lumbar degeneration disease were treated by threaded fusion cage, from May 1997 to May 2002. The JOA scores, the rate of fusion,cage sink and adjacent segment degeneration were observed. Results The average hospitalizotion was 23.59 days. The mean operation time was 3.00 hours. The mean JOA scores were 13.93 before the operation,while 26.69 on the end of the following time respectively; there was statistical significant. The mean motion of operative segment was 5.22 before operation, while 2.44 on the end of the following time respectively. The mean extension of operative segment was 3.32 before operation ,while 1.39 on the end of the following time respectively. The mean motion of adjacent segment was 3.68 before operation, while 6.54 on the end of the following time respectively. The mean extension of adjacent segment was 1.95 before operation,while 3.95 on the end of the following time respectively. There were all statistical significant on those changes of Cobbs angel. Conclusions The long-term therapeuptic effect of WALLIS treatment for lumbar degeneration disease is reliable. The motion of operative segment was significant decreased, especially on extension. The motion of adjacent segment was significant increased, the degree extension of adjacent segment was also significant increased.

Evaluation of posterior pedicle fixation-based dynamic stabilization in treatment of degenerative lumbar disease: Recent progress / 第二军医大学学报

Posterior pedicle fixation-based dynamic stabilization is now densely studied in the non-fusion spine surgery. The method is characterized by the motion preservation of segmental lumbar, avoidance of the stress change after fusion surgery, and adjacent disc degeneration. Posterior pedicle fixation-based dynamic stabilization systems have undergone fast development and are now used for the treatment of degenerative lumbar spine disease. As an innovation of traditional fusion surgery, the clinical evaluation of its efficacy has become a focus of study among spine surgeons. In this paper, we review the recent progress in the clinical efficacy of posterior pedicle fixation-based dynamic stabilization.

Avaliação clínica da estabilização dinâmica com dispositivo Dynesis em pacientes com dor lombar com seguimento mínimo de seis meses / Evaluation of clinical results of dynamic stabilization with the Dynesis dispositive in patients with lumbar pain with a 6 months minimum follow up

Objetivo: Avaliar o resultado clínico da estabilização dinâmica com o dispositivo Dynesis em pacientes com dor lombar e alteração degenerativa do disco intervertebral. Método: Os autores avaliaram 24 pacientes, com idade média de 43,2anos (26 a 57 anos) com queixa de dor lombar com no mínimo seis meses de tratamento conservador sem melhora e ressonância magnética com alteração degenerativa discal avaliado pela classificação de Pffirmann e preservação da altura do disco de pelo menos 40% na radiografia no plano sagital. Foi realizada a fixação com parafuso dinâmico (Dynesis). A avaliação foi realizada por meio da escala visual análoga para dor. Resultado: A escala visual análoga da dor pré-operatoriamente obteve média de 7,4 pontos e após seis meses caiu para 2,9 pontos de média. Conclusão: Neste estudo concluímos que há uma melhora da dor lombar após estabilização dinâmica com dispositivo Dynesis.

The BioFlex System as a Dynamic Stabilization Device: Does It Preserve Lumbar Motion?

OBJECTIVE: This study examines whether functional motion is present at one or more years after Bioflex System placement. BioFlex System is a flexible rod system which has been used to preserve motion at the area of implantation. There has not been a scientific study showing how much motion is preserved after implantation. METHODS: A total of 12 consecutive patients underwent posterior dynamic stabilization using the BioFlex System. Six patients were treated using a L3-4-5 construct and other six patients using a L4-5-S1 construct. Follow-up ranged from 12 to 33 months and standing neutral lateral, extension, flexion and posteroanterior (PA) radiographs were obtained at 3, 6, 9, and 12 months and at more than 12 months postoperatively. Range of motion (ROM), whole lumbar lordosis, and ROMs of motion segments from L2 to S1 were determined. RESULTS: Patients with a L3-4-5 construct demonstrated a decrease in mean ROM for whole lumbar decreased from 40.08 to 30.77. Mean ROM for L3-4 (6.12 to 2.20) and L4-5 (6.55 to 1.67) also decreased after one year. Patients with a L4-5-S1 construct demonstrated L4-5 (8.75 to 2.70) and L5-S1 (9.97 to 3.25) decrease of mean ROM at one year postoperatively. Lumbar lordosis was preserved at both L3-4-5 and L4-5-S1 constructs. Clinical results showed significant improvements in both study groups. CONCLUSION: The present study provides preliminary information regarding the BioFlex motion preservation system. We conclude that the BioFlex System preserves functional motion to some degree at instrumented levels. However, although total lumbar lordosis was preserved, ROMs at implantation segments were lower than preoperative values.

Clinical and Radiological Outcome of an Interspinous Dynamic Stabilization System in Degenerative Lumbar Disease:24 Cases with Over 24 Months of Follow-up

OBJECTIVE: The purpose of this study was to analyze the clinical and radiological outcomes of dynamic stabilization with DIAM implants. METHODS: We evaluated 24 cases in which lumbar decompressive surgery was performed with dynamic stabilization using DIAM and having more than 24 months of follow up. Indications consisted of spinal stenosis with or without a herniated disc and transition level stenosis of the instrumented fusion segment. Operative data, clinical outcome, and plain and flexion/extension radiographs were obtained and compared to preoperative and postoperative data. RESULTS: The mean age at operation was 56.2 years(range 47-68); the mean follow-up duration was 28.4 months(range 24-37 months).The mean pain and function scores improved significantly from baseline to follow-up, as follows: back pain VAS score from 6.2 to 2.5, leg pain VAS score from 7.2 to 2.4, and Prolo's economic and functional rating score from 5.8 to 8.2. Radiological data demonstrated that the heights of the intervertebral foramen and the posterior disc increased significantly after the procedure. There were no implant-associated complications except for two spinous process fractures which occurred during DIAM insertion, and one case of wound infection. Flexion instability and spondylolisthesis occurred in two cases during the follow-up period. CONCLUSION: These mid-term results suggest that DIAM is a safe and effective alternative surgical option in the treatment of degenerative lumbar stenosis without flexion instability. Careful follow-up is needed to watch for the development of flexion instability and spondylolisthesis.

Change of Lumbar Motion after Multi-Level Posterior Dynamic Stabilization with Bioflex System : 1 Year Follow Up

OBJECTIVE: This study examined the change of range of motion (ROM) at the segments within the dynamic posterior stabilization, segments above and below the system, the clinical course and analyzed the factors influencing them. METHODS: This study included a consecutive 27 patients who underwent one-level to three-level dynamic stabilization with Bioflex system at our institute. All of these patients with degenerative disc disease underwent decompressive laminectomy with/without discectomy and dynamic stabilization with Bioflex system at the laminectomy level without fusion. Visual analogue scale (VAS) scores for back and leg pain, whole lumbar lordosis (from L1 to S1), ROMs from preoperative, immediate postoperative, 1.5, 3, 6, 12 months at whole lumbar (from L1 to S1), each instrumented levels, and one segment above and below this instrumentation were evaluated. RESULTS: VAS scores for leg and back pain decreased significantly throughout the whole study period. Whole lumbar lordosis remained within preoperative range, ROM of whole lumbar and instrumented levels showed a significant decrease. ROM of one level upper and lower to the instrumentation increased, but statistically invalid. There were also 5 cases of complications related with the fixation system. CONCLUSION: Bioflex posterior dynamic stabilization system supports operation-induced unstable, destroyed segments and assists in physiological motion and stabilization at the instrumented level, decrease back and leg pain, maintain preoperative lumbar lordotic angle and reduce ROM of whole lumbar and instrumented segments. Prevention of adjacent segment degeneration and complication rates are something to be reconsidered through longer follow up period.

Minimum 2-Year Follow-Up Result of Degenerative Spinal Stenosis Treated with Interspinous U (Coflex(TM))

OBJECTIVE: Clinical and radiological results of posterior dynamic stabilization using interspinous U (ISU, Coflex(TM), Paradigm Spine Inc.(R), NY, USA) were analyzed in comparison with posterior lumbar interbody fusion (PLIF) in degenerative lumbar spinal stenosis (LSS). METHODS: A retrospective study was conducted for a consecutive series of 61 patients with degenerative LSS between May 2003 and December 2005. We included only the patients completed minimum 24 months follow up evaluation. Among them, 30 patients were treated with implantation of ISU after decompressive laminectomy (Group ISU) and 31 patients were treated with wide decompressive laminectomy and posterior lumbar interbody fusion (PLIF; Group PLIF). We evaluated visual analogue scale (VAS) and Oswestry Disability Index (ODI) for clinical outcomes (VAS, ODI), disc height ratio disc height (DH), disc height/vertebral body length x100), static vertebral slip (VS) and depth of maximal radiolucent gap between ISU and spinous process) in preoperative, immediate postoperative and last follow up. RESULTS: The mean age of group ISU (66.2 +/- 6.7 years) was 6.2 years older than the mean age of group PLIF (60.4 +/- 8.1 years; p = 0.003 ). In both groups, clinical measures improved significantly than preoperative values (p 18.6 +/- 5.9%), however decreased significantly in last follow up (13.8 +/- 6.6%, p = 0.027). Vertebral slip (VS) of spondylolisthesis in group ISU increased during postoperative follow-up (2.3 +/- 3.3 --> 8.7 +/- 6.2, p = 0.040). Meanwhile, the postoperatively improved DH and VS was maintained in group PLIF in last follow up. CONCLUSION: According to our result, implantation of ISU after decompressive laminectomy in degenerative LSS is less invasive and provides similar clinical outcome in comparison with the instrumented fusion. However, the device has only transient effect on the postoperative restoration of disc height and reduction of slip in spondylolisthesis. Therefore, in the biomechanical standpoint, it is hard to expect that use of Interspinous U in decompressive laminectomy for degenerative LSS had long term beneficial effect.